On MSNBC Wednesday, San Antonio Mayor Julian Castro, regarded as a rising star by the Democratic Party, compared the status of illegal immigrants in America to that of black slaves before the Civil War.

Castro, the keynote speaker at the 2012 Democratic National Convention, was joined by his brother Rep. Joaquin Castro (D-TX) and was responding to a statement by host Alex Wagner that Democrats condoned extending legal residence or citizenship to America’s eleven million illegal immigrants.

Joaquin agreed, “We’re pushing for full-fledged citizenship. A path to citizenship.” Then Julian chimed in, saying, “It would be unprecedented in American history for us to create a permanent class of folks who are not citizens outside of slavery. And we certainly learned our lesson from that.”

Julian immediately realized the implications of his comparison, and hurriedly added, “I’m not comparing the two in any other sense except to say that we want – we want, in the United States, for folks to be fully invested in our nation.”